1.Japan - nothing change
2.Korea - the same.
Magellan becomes the first European to make contact with these people, about 20 years ahead of the Portuguese, and maybe establishes trade, or, if he doesn't behave himself, or they are in a very bad or suspicious mood, he has a high chance of getting himself killed or arrested or imprisoned for good.
3.Okinawa - they were still practically independent,sl Japan would never conqer them.You have independent Okinawa till in 19th century somebody would turn them into colony,but we have Okinawa with its own nation,and different WW2 war.
Magellan could set a precedent for a Spanish colonial claim to Okinawa. However, the Kingdom was formally a tributary of China, so if the Spanish come later with troops and fly their flag loud and proud, the Ming Chinese might be roused to come send a fleet and kick them out. WW2 doesn't even enter into it.
4.South China - nothing change.
Magellan could set up trade or, if he doesn't behave himself, or they are in a very bad or suspicious mood, he has a high chance of getting himself killed or arrested or imprisoned for good.
Results of 1 thru 4 though may mean there is never Spanish interest in the Philippines and the islands never go by that name.
5.Taiwan - they could take it,but China would take it from them.So,nothing change.
Actually, China didn't seem to care about that "ball of mud in the sea" at that time. So, it could become a substitute for the Philippines, or a northernmost island of them.
6.The Spice islands - Big difference,Spain get more money.And keep it from any other country till 18th century.Maybe they remain superpower longer ? it would change History.
May be hard to avoid a war with Portugal and later the Dutch over this one.
7.Eastern Australia - if they do not found gold there,nothing change - Spain would do not care,so somebody would take it from them in 19th century.If they found gold - see 6.
Thinking this one over, I think Magellan and company are $u#ked if the currents and winds are blowing him to Australia. His ships would be broken up into match-sticks once they run into the Great Barrier Reef and he and his crews will be shark bait.